Process of making pigments.



UNITED STATES Patented Jul 14, 1903.

PATENT Genres.

PROCESS OF MAKING PIGMENTS.

SPECIFICATION forming part of Letters Patent No. 733,612, dated July 14,1903. Application filed October 31, 1902. Serial No. 129,594. (Nospecimens.)

To all whom it may concern.-

Be it known that I, WILLIAM J. ARMBRUS- TER, a citizen of the UnitedStates, residing at St. Louis, State of Missouri, have invented certainnew and useful Improvements in Processes of Making Pigments, of whichthe following is a specification.

Myinvention has relation to improvements in processes of makingpigments; and it consists in the novel series of steps more fully setforth in the specification and pointed out in the claims.

Broadly stated, the process contemplates the successive or simultaneousprecipitation of zinc hydrate and barium sulfate from solutions of Zinc,barium hydrate, and the sulfate of preferably an alkali metal.

As a general illustration of the process I prepare aqueous solutions ofbarium hydrate, zinc nitrate, and sodium sulfate. The barium hydrate andzinc nitrate are brought together, when zinc hydrate is precipitated andbarium nitrate is formed in solution. To-the latter is added the sodiumsulfate, when barium sulfate is precipitated and sodium nitrate formedin solution. The foregoing may be expressed by the following reactions:

It will be readily understood that the acid of the final salt solutionwill correspond to the acid of the zinc salt used, while the base of thefinal solution will correspond to thebase of the sulfate used.

It is not necessary, of course, that the order of bringing the solutionstogether shall be as illustrated above, since the order can be qualifiedwithout departing from the spirit of the invention, thus:

If desired, the respective solutions can be brought togethersimultaneously, thus:

Vhile the precipitates under the last illustration areformed practicallysimultaneously, yet the reactions which take placeare successive, eitherthe barium sulfate being first precipitated with the formation of sodiumhydrate, which then reacts with the zinc salt, precipitating Zinchydrate and forming asodium salt in solution, or the zinc hydrate isfirst precipitated and then the barium sulfate, precedence taking place(as is obvious) according to the relative volumes of the respecti vesolutions present in the reaction. In general, however, the bariumsulfate (owing to its great insolubility) will be precipitated first.

Additional equivalents of barium solution can be added in other than thehydrate form, especially if it is desired to produce a pigment with apreponderance of barium sulfate. This is clearly illustrated by thefollowing reactions:

The additional equivalent of barium solution can even be the sulfid ifit be added after the precipitation of the barium sulfate is affected,thus:

It was stated above that under certain restrictions I may employ thesulfate of zinc in lieu of the nitrate, chlorid, acetate, &c. Thisrestriction is illustrated in the last series of reactions and obviouslyhas reference to the time of adding this reagent-that is to say, it mustbe added so as to avoid double precipitation with the barium hydrateused,

for it is obvious that if the sulfate of zinc were added directly to thebarium hydrate there would result a double precipitate of zinc hydrateand barium sulfate, thus:

a process not contemplated by the present invention. The last reaction,too, illustrates the necessity of adding the sulfid of barium subsequentto the precipitation of the zinc as hydrate, for if added before thezinc would come down as the sulfid, owing to the great affinity betweenthis base and sulfur.

The following reaction may be cited as a further example of the use ofthe sulfate of zinc as the reagent after the barium has beenprecipitated as the sulfate, this reaction also illustrating thepossibility of restoring the composition of the original sulfate used inthe precipitation of the barium, such restored sulfate being capable ofuse in subsequent repetitions of the process, thus:

The sulfate of sodium, as is obvious, can be used in subsequentprecipitations of the barium hydrate, making the process a cyclical one.

The final solution remaining in any case after precipitation is to bedrained from the precipitates and can be recovered in a merchant. bleform by evaporation to a crystalline condition. The recoveredprecipitates are washed, the surplus water separated in any suitablemanner, and the pigment dried if desired. The zine-hydrate constituentcan be converted to zinc oxid in any suitable manner, such as bycalcination, and this may be done either before or after mixture withthe barium sulfate. I may of course invoke the doctrine of chemicalequivalents wherever the same apply.

As a commercial illustration of the process under the first reaction thefollowing may be cited: Separate aqueous solutions are prepared asfollows: zinc nitrate, one hundred and eighty-nine (189) pounds; bariumhydrate, one hundred and seventy-one (171) pounds, and sodium sulfateone hundred and forty-two (H2) pounds. The zinc nitrate and bariumhydrate are brought together, when ninety-nine pounds of zinc hydrateare precipitated and two hundred and sixty one (261) pounds of bariumnitrate are formed in solution. To the latter is added the sodiumsulfatesolution, when two hundred and thirty-three pounds of barium sulfate areprecipitated and one hundred and seventy (170) pounds of sodium nitrateformed in solution. The precipitates and final solution are treated aspreviously described.

The above figures are based on anhydrous salts, the water ofcrystallization being eliminated from the calculations.

Having described my invention, what I claim isl. The process of makingpigment which consists in mixing solutions of barium hydrate and othersoluble barium salts, a salt of Zinc, and a sulfate capable ofprecipitating the barium as a sulfate, substantially as set forth.

2. The process of making pigment which consists in mixing solutions ofbarium hydrate, a salt of zinc other than the sulfate, and a suitablesulfate having a base other than zinc capable of precipitating thebarium as a sulfate, and recovering the resulting precipitates,substantially as set forth.

3. The process of making pigment which consists in mixing solutions ofbarium hydrate, a salt of zinc other than the sulfate, and the sulfateof an alkali metal, and recovering the resulting precipitates,substantially as set forth.

at. The process of making pigment which consists in mixing solutions ofbarium hydrate, a sulfate other than zine capable of precipitating thebarium as a sulfate, then adding a salt of zinc adapted to beprecipitated as the hydrate, and recovering the resulting precipitates,substantially as set forth.

5. The process of making pigment which consists in mixing solutions ofbarium hydrate, zinc nitrate, and sodium sulfate, and recovering theresulting precipitates, substantially as set forth.

6. The process of making pigment which consists in mixing solutions ofbarium hydrate, and a salt of zinc other than the sulfate in thepresence of a sulfate having a base other than zinc whereby the bariumis precipitated as the sulfate, and the zinc as the hydrate,substantially as set forth.

'7. The process of making pigment which consists in mixing solutions ofbarium hydrate and other soluble barium salts, and a salt of zinc, inthe presence of a sulfate whereby the barium is precipitated as thesulfate, and the zinc as the hydrate, substantially as set forth. Intestimony whereof I affix my signature in presence of two witnesses.

IVILLIAM J. ARMBRUSTER. lVitnesses:

EMIL STAREK, G. L. BELFRY.

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